The invention pertains to the protection of components used in an electronic device from electromagnetic interference (EMI), and especially to EMI protection of an interface between a camera and a removable peripheral device, such as a hard drive memory card.
It is highly desirable to provide EMI shielding for a removable peripheral, such as a memory device, in order to suppress the passage of signals into the peripheral that might be picked up by circuitry in the peripheral, and to suppress the radiation of signals by the peripheral or by electronics within the electronic device utilizing the peripheral. The trend in the development of electronic devices, such as cameras, is toward smaller, tightly packed devices. It is usually difficult, if not impossible, to remotely locate and thereby isolate a memory eject interface, as could be done, e.g., in a computer system. Instead the memory device interface lies well within the camera and closely adjacent to camera electronics. Thus it is especially important to isolate the memory device from transmissions and signals that might be generated by circuitry in the camera.
A typical peripheral device is a memory card, such as a hard drive card. Sometimes, the top and bottom covers of the card are formed of conductive material such as stainless steel to provide good EMI shielding. However, PC card peripherals are often not provided with good shielding along the perimeter of the card, that is, the outside of the device between the top and bottom covers. In U.S. Pat. No. 5,333,100 a data card is provided with an electrically conductive rail extending along its opposite sides and part of its rear, and connected to the ground plane of a circuit board on the card, to provide EMI shielding along the perimeter of the card.
In addition, a PC card peripheral is ordinarily attached to digital electronics through an eject interface in the electronic device, which includes an opening in its product enclosure so that the peripheral can be inserted into the device. This opening results in a xe2x80x9chotxe2x80x9d area of EMI susceptibility, as well as a small xe2x80x9cdead airxe2x80x9d region between the sides of the peripheral and the enclosure that can act as an EMI radiator. Moreover, some digital devices, such as a digital camera, are meant to be operable through direct connection to a host computer without use of a PC card peripheral, i.e., without a card inserted into the eject interface. In both cases, EMI can emanate from the unobstructed areas of the opening into the environment, and cause undesirable interference with other devices.
The problem with the current card-based approach is that the camera manufacturer, as well as the camera user, is forced to rely upon the peripheral device (vs. the eject mechanism) for EMI protection. Particularly in the case of tightly packed electronics in a modern digital camera, the performance of the camera may suffer unless EMI protection can be designed into the camera in a fail-safe manner.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, an eject interface for a removable peripheral used in an electronic device includes an eject mechanism for removably receiving the peripheral, a shield for enclosing at least part of the eject mechanism in order to isolate the peripheral from EMI generated by the device, and a grounding connection on the shield for grounding the shield to a circuit ground on the device.
The advantage of the invention is that the shielding allows for the placement of the eject mechanism within the high speed electronics of, e.g., a digital camera. The result is a compact, integral system versus having to remotely locate the eject mechanism.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.